Flushable sanitary napkin

ABSTRACT

A sanitary napkin is disclosed which includes a flushable absorbent pad and an extremely flushable nonwoven fibrous cover that is bonded with a totally water-soluble resinous binder. The cover is reinforced with hot-melt adhesive means in spaced selected generally rectangular zones to increase the wet strength of the cover in areas of high stress which have the probability of being wetted by menstrual fluid, and the increase in wet strength is achieved without impairing the flushability of the cover. The hot-melt adhesive means is applied in spaced discrete lines in each of the zones and the total area of the zones comprises approximately 30 percent of the total area of the cover.

United States Patent [1 1 Srinivasan et al.

[ Oct. 21, 1975 FLUSHABLE SANITARY NAPKIN [73] Assignee: Personal Products Company,

Milltown, NJ.

[22] Filed: Oct. 15, 1974 [21] Appl. N0.: 514,533

[52] US. Cl. 128/290 W; 128/190 R [51] Int. Cl. A61F 13/16 [58] Field of Search 128/285, 290 R, 290 P,

[56] References Cited UNITED STATES PATENTS 2,840,078 6/1958 Smith 128/290 H 3,616,797 11/1971 Champaigne, Jr. et al.... 128/290 W 3,727,615 4/1973 Duchane 128/290 W Primary Examiner-Aldrich F. Medbery Attorney, Agent, or Firm-Jason Lipow [57] ABSTRACT A sanitary napkin is disclosed which includes a flushable absorbent pad and an extremely flushable nonwoven fibrous cover that is bonded with a totally watersoluble resinous binder. The cover is reinforced with hot-melt adhesive means in spaced selected generally rectangular zones to increase the wet strength of the cover in areas of high stress which have the probability of being wetted by menstrual fluid, and the increase in wet strength is achieved without impairing the flushability of the cover. The hot-melt adhesive means is applied in spaced discrete lines in each of the zones and the total area of the zones comprises approximately 30 percent of the total area of the cover.

20 Claims, 5 Drawing Figures us. Patent Oct.21,1975 3,913,579

FLUSHABLE SANITARY NAPKIN BACKGROUND OF THE INVENTION In the sanitary napkin art, there has been a longstanding need and desire for a completely flushable product, i.e., a sanitary napkin that will readilydisintegrate when subjected to excess water and the flushing action of a conventional toilet. This desideratum has been well recognized in the prior art, see for example, U.S. Pat. Nos. 3,521,638, 3,550,592, 3,554,788, 3,610,254, 3,616,797, 3,654,928, and 3,707,430.

Sanitary napkins have conventionally in the past included a nonwoven fabric cover surrounding an absorbent pad of short cellulosic fibers, with a water-repellent layer being provided between the pad and the cover to prevent menstrual fluid from striking through the product. One of the basic problems in providing complete flushability with such a product is to give the cover of the sanitary napkin adequate wet strength so that the product maintains its structural integrity in the presence of body fluid, while at the same time insuring that the components providing the wet strength characteristics will quickly break-down when subjected 'to flushing by a toilet. Various solutions to this problem have been proposed in the above-mentioned patents. However, most of the solutions that have been proposed in the past have been rejected or proven to be unsatisfactory because of either excessive cost, inadequate resistance to wet abrasion, inadequate flushability, inadequate dry and/or wet tensile characteristics, and unsatisfactory softness. Thus, the need remains for a solution to the probelm of providing a commercially feasible completely flushable sanitary napkin.

SUMMARY OF THE INVENTION Like certain of the previously proposed flushable sanitary napkins, the product of the present invention includes an absorbent pad of short cellulosic fibers surrounded by a nonwoven fibrous cover that is bonded with a water-soluble resinous binder. However, the sanitary napkin of the present invention differs significantly from proposed prior art products in that a waterinsoluble reinforcing agent is applied to a substantial area (approximately 30%) of the cover. The reinforcing agent is a hot-melt adhesive that is applied to spaced selected zones of the cover which have the greatest probability of being wetted by menstrual fluid, and the hot-melt adhesive is applied in the form of a plurality of spaced discrete lines within each of the zones.

In the preferred embodiment of the invention, the cover is rectangular in shape and larger than the pad, with'the pad being centered relative to the cover and the side marginal portions of the cover folded over the pad and into overlapping relationship with one another. The ends of the cover extend beyond the ends of the pad and provide tab means for attaching the sanitary napkin to a belt circumscribing the hips of the wearer.

A first of the hot-melt reinforced zones is located generally medially of the cover and is disposed in the center of the pad on the face thereof to be positioned against the body of the wearer. Second and third reinforced zones flank the central zone and are spaced generally equally outwardly therefrom, with the second and third zones each being disposed adjacent one side edge of the pad. The second and third zones are wider than the first zone and are approximately coextensive in length with the pad, with the first zone being somewhat longer than the pad. A fourth reinforced zone of about the same width as the first zone is located along one side marginal edge of the cover and extends from end to end thereof to reinforce the attachment tabs at opposite ends of the sanitary napkin. The hotmelt adhesive lines in each of the reinforced zones in the preferred embodiment of the invention are about oneeighth inch wide and are spaced from one another from about one-eighth inch to about three-eighths inch. Preferably, the lines are rectilinear throughout their length and are parallel with one another. The lines are applied to the interior of the cover, i.e., the surface of the cover directly adjacent to the pad, and do not adversely affect the softness and feel of the cover.

Surprisingly, in spite of the relatively substantial amount of the hot-melt adhesive, the cover is readily disintegratable after soaking in excess water to permit disposal of the sanitary napkin by flushing in a conventional toilet. The increased strength imparted to the product by strategic location and distribution of the hot-melt adhesive is achieved with no sacrifice in softness of the product and with an insignificant effect on flushability. Thus, the present invention provides an economically feasible solution to the troublesome problem that has long plagued skilled workers in the sanitary napkin art, i.e., wet strength and resistance to abrasion in the presence of body fluids and ready disintegratability in the presence of excess water.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspective view of a sanitary napkin formed in accordance with the teachings of the present invention and illustrated in the shape that it assumes while being worn;

FIG. 2 is a perspective view of the sanitary napkin illustrated in FIG. 1 in a flat position suitable for packaging, with a portion of the cover being broken away;

FIG. 3 is a plan view illustrating the inner surface of cover fabrics laid out flat as manufactured for use with the sanitary napkin of the present invention;

FIG. 4 is an enlarged end view of the cover fabric shown in FIG. 3 with the inner surface facing downward; and

FIG. 5 is an enlarged cross-sectional view taken generally along lines 5-5 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

Referring now to the drawings, the sanitary napkin 10 of the present invention includes an absorbent pad or core 12 encased within a fluid pervious cover 14. As can be best seen in FIGS. 1 and 5, a barrier sheet 16 overlies the sides and the bottom surface of absorbent pad 12 (the bottom surface being the portion of the napkin facing away from the body of the wearer). Pad

12 is formed of absorbent fibrous material such as comminuted wood pulp fibers, cotton linters, rayon fibers, cotton staple, bleached sulfite linters, and other cellulosic or modified cellulosic fibers and the like. The exact structure of pad 12 is' not critical to the present invention, and the pad may include multiple plies and- /or densified cellulosic portions, as taught, for example, by U.S. Pat. Nos. 2,952,260, 3,017,304, 3,060,936, and 3,494,362. It should also be understood that the absorbent core may comprise, in addition to the absorbent pad 12 and barrier sheet 16, a fluid pervious element such as gauze, tissue and the like if increased strength and/or dimensional stability are desired.

Barrier sheet 16 is a thin film which is resistant to body fluids so as to prevent menstrual fluid from striking through the cover of the sanitary napkin. The film is dispersible in water, and may be constructed in accordance with the teachings of U.S. Pat. No. 3,800,797 issued on Apr. 2, 1974 to Deger Tunc, the disclosure of which is hereby incorporated herein in its entirely by this reference. Other suitable water dispersible films will suggest themselves to those skilled in the art.

Pad 12 is generally rectangular in shape, both in cross section and plan view, and the end and side portions of the pad may be rounded for enhanced comfort to the wearer. Cover 14 is also preferably rectangular in shape as can be best seen in FIG. 3, and cover 14 is larger than pad 12 both in length and width, with the pad being generally centrally disposed with respect thereto. The opposite side marginal edges 18 and 20 of cover 14 are folded over pad 12 and into overlapping relationship with one another to encase the pad and to provide tab means 22 and 24 at opposite ends of the napkin for attachment to a support belt circumscribing the hips of the wearer.

Cover 14 is a nonwoven fibrous member bonded with a watersoluble resinous binder so as to be inherently dispersible in excess water. While many different types of fluid pervious nonwoven fabrics are suitable for use as a cover for the sanitary napkin of the present invention, the cover is preferably an apertured nonwoven fabric such as those disclosed in U.S. Pat. Nos.

2,862,251, 3,129,466, 3,193,436, 3,081,515, 3,081,514, 3,081,512, 3,081,500, 3,068,547, 3,059,313, 3,681,182, 3,681,183, 3,681,184 and 3,682,756.

Typical water-soluble polymers, useful as binders for the nonwoven covers include water-soluble vinyl polymers, such as polyvinyl alcohol and polyvinyl pyrrolidone; polymers of acrylic acid and its homologs, such as polyacrylic acid and polymethacrylic acid; modified starches, such as dextrins, hydroxyethyl starch ethers, amine starches, phosphate starches and starch acetates; cellulose derivatives including carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, and epoxy derivatives of cellulose; natural gums and alginates, including gum arabic and sodium alginate; polyacrylamide; polyethylene oxide; polyethyleneimine; polyacrylonitrile; and saponified copolymers of ethylene and vinyl acetate.

Cover 16 is reinforced in spaced selected generally rectangular zones by a water-insoluble hot-melt adhe' siveto increase the wet strength of the cover in those areas which have the greatest probability of being wetted by menstrual fluid. The term hot-melt as used herein is intended to mean any adhesive base that can be readily softened by moderate heating without degradation of the base itself and which can be melted and applied in molten form to the cover. Typical waterinsoluble thermoplastic polymers useful as hot melt adhesives include polyolefins such as low-density polyethylene and polyisobutylene; polyamides, polycarbonates; polyesters; polyurethanes; polystyrene; acrylic polymers; copolymers of ethylene and vinyl acetate; and copolymers of ethylene and ethyl acrylate. As with other types of adhesives, various additives may be added to increase tackiness, flexibility, or flow properties during application. Such adhesives are advantageous in that they contain no water or expensive solvents that must later be removed and furthermore, such adhesives are extremely fast setting because simple cooling is all that is required to develop bond strength.

With reference to FIG. 3, a first zone 26 is located generally medially of the-cover l4 and second and third zones 28 and 30 are spaced generally equally outwardly from zone 26. Zones 28 and 30 are generally equal in length and width and are wider and shorter than central zone 26. A fourth zone 32 is provided along cover side marginal edge 18 and extends from end to end thereof, with the zone 32 being generally equal in width to central zone 26.

Zone 26 is provided on the face of the napkin that is to be positioned adjacent the body of the wearer and provides reinforcement in the area that directly receives the body fluid discharge and which is stressed significantly by normal functions of the wearer. Zone 26 extends beyond the end portions of the pad to protect against the possibility of fluid wicking in the coverv beyond the ends of the pad. Zones 28 and 30 are gener: ally coextensive in length with the sides of the pad, and provide reinforcement against the considerable abrasion that is imparted to these portions of the cover by rubbing against an undergarment or against the body when the napkin assumes the position shown in FIG. 1..

Zone 32 provides reinforcement in the attachment tabs 22 and 24, which are sometimes struck with menstrual fluid by misplacement of the napkin or by an endfailure of the pad.

As is evident from FIGS. 3 and 4, the hot-melt adhesive in each of zones 26, 28, 30 and 32 is applied in the form of a plurality of spaced discrete lines. And, from FIG. 5, it is clear that the adhesive lines are applied, such as by extruding, to the inside of the cover, i.e, the surface of the cover that faces pad 12. With this arrangement any possible adverse affect on the softness and feel of the cover is minimized. The lines within each of the zones are illustrated as being continuous and rectilinear throughout their length and parallel with one another and with the side marginal edges of the cover. Although it is not preferred, it is contemplated that in certain instances, the lines could be discontinuous and/or curvilinear or non-parallel.

In a most preferred embodiment of the invention,the lines within each of the zones are of equal width and are spaced equally from one another. The overall area of zones 26, 28, 30 and 32 represents a significant, although minor, portion of the total area of cover 14, and it has been found that when the reinforced zones comprise as much as 30% of the total area of the cover, there is only an insignificant effect on the flushability of the cover, with the result that a sanitary napkin made from such a cover can be readily disposed of in a conventional toilet.

Sanitary napkins constructed in accordance with the teachings of the present invention were prepared fortesting by using the padconstruction of a commercially available flushable napkin sold by Personal Products Co., Milltown, New Jersey, a corporation of the State of New Jersey, as MODESS flushable feminine nap kins, and such pads were wrapped with a nonwoven fabric made with rayon fiber and bonded with a water- 6 poses. The testing system comprises an American Standard Toilet fitted with 3 inch (l.D.) copper piping, approximately 9 feet long. This pipe was connected to the toilet by way of an elbow and a suitable length of vertisoluble alginate binder of about 15 percent add-on 5 cally placed piping. At the opposite end of the pipe, based on the weight of the web and distributed uniand at right angles thereto, was placed an exit pipe formly in the web. Polyethylene based hot-melt adheabout 20 inches long. A tubular wire mesh screen, sive was applied to the cover in about 6.27 weight perabout 18 inches long, was concentrically placed within cent based on the weight of the web, as a series of lines the exit pipe, the screen carrying several rows of barbs along the machine direction of the fabric. The hot-melt to simulate any internal rough surfaces in a sewage sysadhesive lines were approximately one-eighth inch tem. The test was conducted by dropping the sanitary wide and the spacing therebetween was varied from napkin into the toilet bowl, waiting seconds, and one-eighth inch to three-eighths inch in one-sixteenth then flushing. After each napkin was flushed, the inch increments. The fabrics were tested for resistance screen was removed and the residue thereon was visuto wet abrasion and flushability, and were comparedto 15 ally rated by comparison with a set of standard photoa control fabric which was the same fabric without any graphs. A flushability rating of excellent (1), good (2), reinforcement. fair (3) or poor (4) was then assigned to the napkin under test. In addition to the hot-melt reinforced cov- WET ABRASION ers, a napkin pad without a cover was flushed as a refer- In order to simulate and measure in-use wet abrasion, 20 ence, and a napkin with a conventional flushable matesamples of 7 inches (machine direction) and 3 inches rial as a cover fabric was also flushed. Average ratings (cross direction) of cover fabrics as described in the for six readings for the samples are given in Table II. preceeding paragraph were saturated with water and TABLE tested on a Stol abrasion tester with the motion of the tester parallel to the machine direction of the fabric. Fabric Average Rating Standard 80 X 80 cotton was used as the stationary sur- None (pad only) 1.3 (Good Excellent) face, and the area of contact was a 1% inch diameter cnveminal C Fair) Control (no reinforcement) 1.7 (Good) circle. Samples were abraded in 0, 10, 20, 50 and 100 between lines 10 (Good) cycles, dried, and the machine direction tensile ih f 'gg :8 (ga g; strength measured on a Instron tensile tester. The refi g 'fifii (602d) sults of the tensile strength (averages of six tests) are 3/8" between lines 1.7 (Good) reported .in Table I, which also shows the percent loss of tensile strength with respect to the 0 cycle reading. All of the reinforced samples showed higher tensile This data shows that the addition of hot-melt as a restrengths after abrasion at each cycle reading than the inforcement did not significantly hinder the flushability control fabric without hot-melt reinforcement. It of the napkin as compared with the control. All of the should be noted that in this test, the maximum loss in test samples proved to be extremely more flushable tensile strength is never 100 percent because the samthan the conventional cover. ple width is greater than the diameter of the abraded PANEL TEST area; however, a hole was produced in the center of the 40 sample with the control fabric at 50 cycles which added Sanitary napkins constructed as described above with a 64.9 percent loss of tensile strength. one-eighth inch hot-melt adhesive lines spaced from The data set forth in Table 1 indicates that a napkin one another by three-sixteenths inch in each zone were cover bonded with a water-soluble binder performs submitted for panel testing, and the results are shown in much better under menstrual conditions when rein- Table III below. forced with hot-melt in the areas which are most sub- TABLE In ject to wet abrasion. The amount of increase of resistance to wet abrasion is dependent upon the number of f g ig' kggi z hot-melt lines and the distance between them.

TABLE 1 Control l/8" 3/16" l/4" 5/16" 3/8" No. of Tens. Tens. Tens. Tens. Tens. Tens. Cycles Str. Loss Str. Loss Str. Los Str. Loss Str. 7: Loss Str. Loss 0 7.50 0.0 11.83 0.0 11.19 0.0 10.51 0.0 10.18 0.0 9.38 0.0 10 3.60 52.0 8.36 29.3 7.56 32.4, 6.56 37.6 5.73 43.7 6.43 31.5 20 2.66 64.5 7.48 36.8 8.13 27.3 6.86 34.7 5.53 45.7 5.93 36.8 2.63 64.9 6.64 43.9 7.49 33.1 6.03 42.6 5.24 48.5 5.36 42.9

.NOTE: Tens. Str. Tensile Strength is measured in the machine direction and has the units lbs/3 "width. Loss is based on the loss of tensile strength in relation to the 0 cycle reading. Completely abraided at 50 cycles.

FLUSHABILITY Average time of use 5.01 5.43 Sanitary napkins constructed as described above thr.) h ffl were prepared and tested for flushability by flushing gg'gg z f f 436 5.50 them through a testing system designed for such pur- Napkins severely 5.6 22.2

TABLE Ill-continued Hot Melt Reinforced Napkins Commercial Napkins abraded SOFTNESS Napkins as described above with hot-melt reinforced covers wherein the adhesive lines were spaced apart one-eighth inch and five-sixteenths inch in the reinforced zones were submitted for panel testing, and the results of the tactile test show that the napkins with hotmelt reinforced covers were preferred over the conventional commercially available napkins.

From the foregoing, it should be clear that there is a total absence of hot-melt adhesive in a major portion of the cover fabric, and that those areas which are reinforced with hot-melt are self-contained separate and distinct zones with significant areas therewithin having fibers that are not contacted by the hot-melt material. The absence of hot-melt materials in a major portion of the cover fabric, and the confinement of the hot-melt material to only a portion of the reinforced zones provides the dually advantageous result of ready flushability and improved resistance to abrasion. And, the total absence of hot-melt outwardly of zones 28 and 30 is significant, since the cover fabric remains compliant enabling pleats 34 and 36 to be easily formed in the cover adjacent the corners of the pad.

In the broader aspects of the invention, cover 14 need not be longer than pad 12, since a similar selectively reinforced cover also has applicability with a tabless product, e.g., a sanitary napkin where tabs are not used as attachment means and other attachment means such as,-for example, adhesive means is also used. Also,

cover 14 need not completely surround pad 12, and instead, the side edges of the cover could extend over the side edges of barrier sheet 16, in which case the barrier sheet and fluid pervious cover would cooperate to collectively form an enclosure for the pad. And, the concept of selective reinforcability is also applicable to light-weight nonflushable nonwoven fabrics, since such fabrics can be given adequate wet and dry strength at reduced costs by significantly reducing the quantity of fibers in the fabric.

What is claimed is:

l. A sanitary napkin comprising: a generally rectangularly shaped absorbent pad; a nonwoven fibrous cover surrounding said pad, said cover being rectangular in shape and larger than said pad, the opposite side marginal edges of said cover being folded over said pad and into overlapping relationship with one another, the opposite end edges of said cover extending beyond the ends of said pad and providing attachment tab means, said fabric being bonded with a water-soluble resinous binder; and hot-melt adhesive means applied to spaced selected generally rectangular zones of said cover for reinforcing said cover against wear in said zones, a first of said zones being located generally medially of said cover and disposed generally centrally of said pad on the face thereof to be positioned against the body of the wearer, a second and a third of said zones being spaced generally equally outwardly of said generally medially located zone and disposed in a position adjacent the opposite side edges of the pad, and a fourth of said zones being located along one side marginal edge of said cover and extending from end to end thereof to provide reinforcement in said attachment tab means, the areas of said cover outwardly of said zones being free of said hot-melt adhesive means whereby said cover is disintegratable after soaking in excess water to permit diposal by flushing.

2. A sanitary napkin as set forth in claim 1 wherein said spaced selected zones comprise approximately 30% of the area of said cover.

3. A sanitary napkin as set forth in claim 1 wherein said hot-melt adhesive means is applied in spaced discrete lines within said zones.

4. A sanitary napkin as set forth in claim 3 wherein said lines are about one-eighth inch wide and are spaced from one another by about three-sixteenths inch.

5. A sanitary napkin as set forth in claim 1 wherein the total area of said selected zones comprises a minor portion of the total area of said cover, and wherein said hot-melt adhesive means is applied in spaced discrete lines within said zones.

6. A sanitary napkin as set forth in claim 1 wherein said first zone of hot-melt adhesive means is at least as long as said pad.

7. A sanitary napkin as set forth in claim 6 wherein said first zone of hot-melt adhesive means extends beyond the ends of said pad.

8. A sanitary napkin as set forth in claim 1 wherein said second and third zones are generally coextensive in length with the adjacent side edge of the pad.

9. A sanitary napkin comprising: an absorbent pad; a nonwoven fibrous cover surrounding said pad; and hotmelt adhesive means applied to spaced selected generally rectangular zones of said cover for reinforcing said cover against wear in said zones, the total area of said selected zones comprising a minor portion of the total area of said cover, a first of said zones being located generally medially of said cover and disposed generally centrally of said pad on the face thereof to be positioned against the body of the wearer, and a second and a third of said zones being spaced generally equally outwardly of said generally medially located zone and disposed in a position adjacent the opposite side edges of the pad, the areas of said cover outwardly of said zones being free of said hot-melt adhesive means and each of said zones including a plurality of spaced discrete lines of hot-melt adhesive means.

10. A sanitary napkin as set forth in claim 9 in which the opposite end portions of the cover extend beyond the opposite ends of the pad to provide attachment tab means and wherein hotmelt adhesive means is applied to the opposite end portions of said cover to reinforce said attachment tab means.

11. A sanitary napkin as set forth in claim 10 wherein said cover is rectangular in shape and larger than said pad, the opposite side marginal edges of said cover being folded over said pad and into overlapping relationship with one another.

12. A sanitary napkin as set forth in claim 11 wherein said attachment tab means are reinforced by a fourth zone of hot-melt adhesive means located along one side marginal edge of said cover and extending from end to end thereof.

13. A sanitary napkin as set forth in claim 10 wherein said cover is bonded with a water-soluble resinous binder whereby said cover is disintegratable after soaking in excess water to permit disposal by flushing.

14. A sanitary napkin comprising: a generally rectangularly shaped absorbent pad; a nonwoven fibrous cover surrounding said pad, said cover being rectangular in shape and larger than said pad, the opposite side marginal edges of said cover being folded over said pad and into overlapping relationship with one another, the opposite end edges of said cover extending beyond the ends of said pad and providing attachment tab means, said fabric being bonded with a water-soluble resinous binder; and a hot-melt adhesive means applied to spaced selected generally rectangular zones of said cover for reinforcing said cover against wear in said zones, the total area of said zones comprising a minor portion of the total area of said cover, a first of said zones being located generally medially of said cover and disposed generally centrally of said pad on the face thereof to be positioned against the body of the wearer, a second and a third of said zones being spaced generally equally outwardly of said generally medially located zone and disposed in a position adjacent the opposite side edges of the pad, said first, second and third zones each being at least as long as said pad, and a fourth of said zones being located along one side marginal edge of said cover and extending from end to end thereof to provide reinforcement in said attachment tab means, said hot-melt adhesive means being applied in the form of a plurality of spaced discrete lines within each of said zones and the area of said cover outwardly of said zones being free of said hotmelt adhesive means, whereby said cover is disintegratable after soaking in excess water to permit disposal by flushing.

15. A sanitary napkin as set forth in claim 14 wherein said second and third zones are generally equal in length, and said first zone is longer than said pad and said second and third zones.

16. A sanitary napkin as set forth in claim 14 wherein said second and third zones are generally equal in length and width.

17. A sanitary napkin as set forth in claim 16 wherein said first zone is narrower and longer than said second and third zones.

18. A sanitary napkin as set forth in claim 17 wherein said lines are about one-eighth inch wide and are spaced from one another by about three-sixteenths inch.

19. A sanitary napkin as set forth in claim 14 wherein each of said lines is continuous throughout its length.

20. A sanitary napkin as set forth in claim 14 wherein said lines are rectilinear and parallel with one another. =l =l UNITED STATES PATENT AND TRADEMARK OFFICE QERTIFICATE OFTCORRECTION PATENT NO. 1 3,913,579

DATED 2 October 21, 1975 lN\/ ENTOR(S) Scrinivasan, Subramaniem & Sivilich, Daniel M.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: 0

The inventor's name "Subramani Srinivasan" should be"Subra.ma:nian Srinivasan" In Column 1, line 33, the word "probelm" should read "problem" U In Column 3, line 17, the word "entirely" should read "ent:rrety In Column 5, Table I Under 5/16" Tens. sum, the numbers v4.35" should read "#26" Q In Column 8, line 10, the word "diposal" should read "disposal" Signed and Sta ed rhfie I {D twenty-second Day Of June 1976 [SEAL] A nest:

RUTH C. MA SON C. MARSHALL DANN Arresting Ojjrcer Commissioner oflatents and Trademark; 

1. A sanitary napkin comprising: a generally rectangularly shaped absorbent pad; a nonwoven fibrous cover surrounding said paD, said cover being rectangular in shape and larger than said pad, the opposite side marginal edges of said cover being folded over said pad and into overlapping relationship with one another, the opposite end edges of said cover extending beyond the ends of said pad and providing attachment tab means, said fabric being bonded with a water-soluble resinous binder; and hot-melt adhesive means applied to spaced selected generally rectangular zones of said cover for reinforcing said cover against wear in said zones, a first of said zones being located generally medially of said cover and disposed generally centrally of said pad on the face thereof to be positioned against the body of the wearer, a second and a third of said zones being spaced generally equally outwardly of said generally medially located zone and disposed in a position adjacent the opposite side edges of the pad, and a fourth of said zones being located along one side marginal edge of said cover and extending from end to end thereof to provide reinforcement in said attachment tab means, the areas of said cover outwardly of said zones being free of said hot-melt adhesive means whereby said cover is disintegratable after soaking in excess water to permit diposal by flushing.
 2. A sanitary napkin as set forth in claim 1 wherein said spaced selected zones comprise approximately 30% of the area of said cover.
 3. A sanitary napkin as set forth in claim 1 wherein said hot-melt adhesive means is applied in spaced discrete lines within said zones.
 4. A sanitary napkin as set forth in claim 3 wherein said lines are about one-eighth inch wide and are spaced from one another by about three-sixteenths inch.
 5. A sanitary napkin as set forth in claim 1 wherein the total area of said selected zones comprises a minor portion of the total area of said cover, and wherein said hot-melt adhesive means is applied in spaced discrete lines within said zones.
 6. A sanitary napkin as set forth in claim 1 wherein said first zone of hot-melt adhesive means is at least as long as said pad.
 7. A sanitary napkin as set forth in claim 6 wherein said first zone of hot-melt adhesive means extends beyond the ends of said pad.
 8. A sanitary napkin as set forth in claim 1 wherein said second and third zones are generally coextensive in length with the adjacent side edge of the pad.
 9. A sanitary napkin comprising: an absorbent pad; a nonwoven fibrous cover surrounding said pad; and hot-melt adhesive means applied to spaced selected generally rectangular zones of said cover for reinforcing said cover against wear in said zones, the total area of said selected zones comprising a minor portion of the total area of said cover, a first of said zones being located generally medially of said cover and disposed generally centrally of said pad on the face thereof to be positioned against the body of the wearer, and a second and a third of said zones being spaced generally equally outwardly of said generally medially located zone and disposed in a position adjacent the opposite side edges of the pad, the areas of said cover outwardly of said zones being free of said hot-melt adhesive means and each of said zones including a plurality of spaced discrete lines of hot-melt adhesive means.
 10. A sanitary napkin as set forth in claim 9 in which the opposite end portions of the cover extend beyond the opposite ends of the pad to provide attachment tab means and wherein hotmelt adhesive means is applied to the opposite end portions of said cover to reinforce said attachment tab means.
 11. A sanitary napkin as set forth in claim 10 wherein said cover is rectangular in shape and larger than said pad, the opposite side marginal edges of said cover being folded over said pad and into overlapping relationship with one another.
 12. A sanitary napkin as set forth in claim 11 wherein said attachment tab means are reinforced by a fourth zone of hot-melt adhesive means located along one side marginal edge of said cover and extending fRom end to end thereof.
 13. A sanitary napkin as set forth in claim 10 wherein said cover is bonded with a water-soluble resinous binder whereby said cover is disintegratable after soaking in excess water to permit disposal by flushing.
 14. A sanitary napkin comprising: a generally rectangularly shaped absorbent pad; a nonwoven fibrous cover surrounding said pad, said cover being rectangular in shape and larger than said pad, the opposite side marginal edges of said cover being folded over said pad and into overlapping relationship with one another, the opposite end edges of said cover extending beyond the ends of said pad and providing attachment tab means, said fabric being bonded with a water-soluble resinous binder; and a hot-melt adhesive means applied to spaced selected generally rectangular zones of said cover for reinforcing said cover against wear in said zones, the total area of said zones comprising a minor portion of the total area of said cover, a first of said zones being located generally medially of said cover and disposed generally centrally of said pad on the face thereof to be positioned against the body of the wearer, a second and a third of said zones being spaced generally equally outwardly of said generally medially located zone and disposed in a position adjacent the opposite side edges of the pad, said first, second and third zones each being at least as long as said pad, and a fourth of said zones being located along one side marginal edge of said cover and extending from end to end thereof to provide reinforcement in said attachment tab means, said hot-melt adhesive means being applied in the form of a plurality of spaced discrete lines within each of said zones and the area of said cover outwardly of said zones being free of said hotmelt adhesive means, whereby said cover is disintegratable after soaking in excess water to permit disposal by flushing.
 15. A sanitary napkin as set forth in claim 14 wherein said second and third zones are generally equal in length, and said first zone is longer than said pad and said second and third zones.
 16. A sanitary napkin as set forth in claim 14 wherein said second and third zones are generally equal in length and width.
 17. A sanitary napkin as set forth in claim 16 wherein said first zone is narrower and longer than said second and third zones.
 18. A sanitary napkin as set forth in claim 17 wherein said lines are about one-eighth inch wide and are spaced from one another by about three-sixteenths inch.
 19. A sanitary napkin as set forth in claim 14 wherein each of said lines is continuous throughout its length.
 20. A sanitary napkin as set forth in claim 14 wherein said lines are rectilinear and parallel with one another. 